1. Field of the Invention
This invention relates to an orthodontic buccal tube adapted for use with wire having either a round or rectangular cross-section.
2. Description of the Related Art
During orthodontic therapy, buccal tubes are secured to the molar teeth to hold the ends of an arch wire in place. The arch wire is guided through slots in brackets fixed to anterior, cuspid and bicuspid teeth, and forms a track to guide the movement of the teeth.
Orthodontic arch wire typically has either a rectangular or round cross-section. Rectangular arch wire is useful when placed in brackets having matching rectangular slots so that the wire can apply torque to the brackets to accomplish certain movement of the teeth. On the other hand, it may be desirable to utilize round wire to accomplish movement of the teeth where torquing forces are not involved. In some instances, the orthodontist may use a round wire during earlier stages of treatment, and then switch to a rectangular wire at a later time.
The buccal tube may also have a passage for receiving an auxiliary wire such as headgear wire, a lip bumper or a segmented arch wire in addition to a channel for receiving the main arch wire. Typically, headgear wire and lip bumper wire have a round cross-section, while segmented arch wire has a rectangular cross-section. Consequently, if initial treatment includes headgear or a lip bumper which is later replaced with a segmented arch wire, the buccal tubes initially mounted on the molars for receiving round wires are often removed and replaced with buccal tubes adapted to receive rectangular wires. Such practice, however, is costly and time consuming. Another option is to utilize a double buccal tube appliance having a round tube and rectangular tube mounted side-by-side on a single base, but such an arrangement is too large in some cases and requires the ends of one of the wires to be bent to fit the offset between the two tubes.
A convertible buccal tube assembly is described in U.S. Pat. No. 4,781,582 and includes a cylindrical tube along with a flap having a rectangular opening. The flap may be bent to a position on the mesial side of the opening to the cylindrical tube so that torquing forces can be applied between rectangular arch wire and the buccal tube. The flap may also be bent to an out-of-the-way location in order to insert round wire into the cylindrical opening. However, the assembly described in U.S. Pat. No. 4,781,582 presents certain manufacturing difficulties and also requires some additional time and effort of the orthodontist whenever the arch wire is changed from round to rectangular or vice versa.